How should ferromagnetic particles be applied for magnetic particle inspection?

In magnetic particle inspection, ferromagnetic particles are effective in revealing surface and near-surface discontinuities in ferromagnetic materials. The correct method for applying these particles is through either a liquid suspension or in dry powder form.

Using a liquid suspension allows the particles to circulate freely and to easily penetrate any surface irregularities due to the fluid's ability to cover the entire area being inspected. This method provides uniform coverage and ensures that the particles can settle into any cracks or defects. On the other hand, dry powder can also be used effectively but might require a different approach to ensure adequate coverage and penetration into defects.

Combining these two methods allows for versatility during inspections, depending on the specific requirements of the component and the magnitude of the defects being examined. The other application methods, such as spraying from a distance or using a brush, might not provide the necessary control or thoroughness in distributing the particles effectively across the surface area being inspected.